Assessment of the Polychlorinated Biphenyl (PCB) Occurrence in Copper Sulfates and the Influential Role of PCB Levels on Grapes

<div><p>Copper sulfates (CuSO₄) are widely used as the primary component of fungicides in the grape industry. The agricultural-grade CuSO₄ that we collected from Chinese nationwide markets were found to be contaminated by polychlorinated dibenzo-<i>p</i>-dioxins and dibenzofurans and high levels of polychlorinated biphenyls (Σ₁₉PCBs: 0.32~9.51 ng/g). In the following research, we studied the impact of CuSO₄ application on PCB levels in grape products through a field experiment, and conducted a national survey to speculate the role that CuSO₄ played on the occurrence of PCB in grapes. In the field experiment, an obvious increase of PCBs in grape leaves (from 174 to 250 pg/g fw) was observed after Bordeaux mixture (the main component of which is CuSO₄) application. As to the main PCB congener in CuSO₄, the most toxic CB 126 (toxic equivalency factor = 0.1) also increased in grape peels (from 1.66 to 2.93 pg/g fw) after pesticide spray. Both the correlation study and the principal component analysis indicated that environmental factors were dominant PCB contributors to grapes, and grapes from e-waste dismantling area containing the highest PCBs also proved the notion. It is worth noting that this report describes the first research examining PCBs in CuSO₄ and its influence on agricultural products to date.</p></div

Concentrations of Σ₁₇PCDD/Fs and Σ₁₉PCBs in agricultural-grade (n = 10) and analytical-grade (n = 4) CuSO₄.

<p>The box upper and under lines represent the 25th and 75th percentiles, respectively, and the three horizontal bars represent the 5th, 50th, and 95th percentiles. * represent the 1% and 99%, □ represent mean values.</p

Descriptions of sampling project and corresponding sample IDs in the field experiment.

<p>Descriptions of sampling project and corresponding sample IDs in the field experiment.</p

The (a) loading plot and (b) score plot of the principle component analysis (PCA) of PCBs in field grape peels, grape pulps, grape leaves, air, soil and copper sulfate samples after BM application.

<p>C1 and C2 were the CuSO₄ used in the field experiment; A7 was the passive air sampler in experimental area during July 28th~November 5^th; P10-P12, U10-U12 and L7-L8 were the grape peels, pulps and leaves obtained after BM spray in experimental area respectively.</p

Antibody-Free Colorimetric Detection of Total Aflatoxins in Rice Based on a Simple Two-Step Chromogenic Reaction

The prevalently used immunoassays for fast screening of aftatoxins (AFs) usually cannot meet the requirement for simultaneous determination of total AFs (aflatoxin B₁ + aflatoxin B₂ + aflatoxin G₁ + aflatoxin G₂) due to the deficiency of highly group-specific antibodies. This paper describes a two-step chromogenic reaction based method to quantitatively detect total AFs in rice using colorimetric measurement without antibody. In the method, colorless AFs transform into green-colored indophenol products through the reaction with sodium hydroxide and 2,6-dibromoquinone-4-chloroimide (DBQC) successively, allowing selectively determining total AFs up to 3.9 μg/kg over other competitive mycotoxins under optimal conditions by a UV–vis spectrophotometer. In addition, the colorimetric measurement results of the rice samples agree well with that of a standard HPLC method, demonstrating the good reliability and applicability of the method. Uniquely, the method has potential for on-site detection of total AFs in rice when using a nylon membrane-based device